Stator Core and Frame Modal Analysis of a High Power Generator

In this study, various types of frequencies for modal analysis of electrical machines are defined. Then equivalent core modeling of a generator for vibration analysis will be examined. For modeling the equivalent core, it should be considered that the mass, outer diameter, and moment of inertia are the same as the original core. The boundary conditions for the modal analysis modeling will be justified thoroughly. It will be shown that when a turbo-generator is attached to a much heavier mass (i.e., the foundation), the heavy mass can be neglected, and the boundary condition of the light mass can be considered as fixed support. After that, modal analysis of the core and base-frame of the generator will be calculated by use of finite element analysis (FEA). Global and local frequencies and corresponding mode shapes of the structure are investigated and reported. The results show that the global frequencies are far enough from the excitation frequencies (50 and 100 Hz). Besides, it can be seen that the design is high-frequency tuning. Finally, some solutions are presented to improve the design of the structure.